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MAGNETIC STORM STILL POSSIBLE THIS WEEKEND: Despite a very quiet weekend so far, NOAA forecasters are still predicting geomagnetic activity in response to an incoming solar wind stream. The odds of a polar geomagnetic storm on Jan. 18th are as high as 50%. Arctic sky watchers should be alert for Northern Lights. Aurora alerts: text, voice
INCREDIBLY LONG COMET TAIL: Standing under the stars in the countryside, people are looking up and seeing the green head of Comet Lovejoy not far from the Pleiades star cluster. There's also a hint of a tail, faint but long. Note to sky watchers: It's even longer than you think. Astrophotographers doing long exposures of the comet find that the tail extends an incredible 15o to 20o across the night sky. Alan Dyer, author of "How to Shoot Nightscapes and Timelapses", sends this picture from City of Rocks State Park, New Mexico:
"These images from show just how marvellous Comet Lovejoy's blue ion tail has become, at least to the eye of the camera," says Dyer. " It now stretches back at least 15°, perhaps as much as 20° with 'averted imagination'!" Click here to learn more about Dyer's photo settings.
For reference, a 20o long tail would stretch along the entire length of the Big Dipper, from handle to bowl. It is 40 times as wide as the full Moon.
Many observers have noted the similar colors of the Pleiades and the comet's tail. Both are a beautiful shade of cosmic blue. Despite their similar appearance, however, the two blues come from different physics. The comet's tail is blue because it contains ionized carbon monoxide (CO+), a gas which fluoresces blue in the near-vacuum of interplanetary space. The nebulosity surrounding the Pleiades is blue because grains of interstellar dust embedded in the gas scatter the blue light of hot young stars at the cluster's core.
Need help finding the comet? Check these finder charts from Sky & Telescope. Also, the Minor Planet Center has published an ephemeris for accurate pointing of telescopes.
Realtime Comet Photo Gallery
SOMETHING AMAZING HAPPENING AT JUPITER: Jupiter and Earth are converging for a (relatively) close encounter in early February when the giant planet is at opposition--that is, directly opposite the sun in the midnight sky. This sets the stage for an extraordinary sequence of events. For the next couple of months, backyard sky watchers can see the moons of Jupiter executing a complex series of mutual eclipses and transits. Astrophotographer "Shiraishi" Kumagaya-shi, Saitama, Japan, captured this example on Jan. 17th:
"First, Ganymede partially eclipsed Callisto; then Europa partially eclipsed Io," says Shiraishi. "I did not need a telescope. To photograph this double mutual event, I used a Nikon Coolpix P510 digital camera set at ISO 800 for a series of 1/10s exposures."
The moons of Jupiter will be passing in front of one another and in front of Jupiter with fair frequency through March 2015 and beyond. This is happening because Jupiter's opposition on Feb. 6th coincides almost perfectly with its equinox on Feb. 5th (when the Sun crosses Jupiter's equatorial plane). It is an edge-on apparition of the giant planet that lends itself to eclipses, occultations and transits.
The next big event is right around the corner. On Jan. 24, 2015, beginning at approximately 06:26 UT (1:26 AM EST), the three moons Io, Callisto and Europa will simultaneously cast their inky shadows on Jupiter's cloudtops. This is called a "triple shadow transit," and it is rare. The timing favors observers in North America where the planet will be shining high in the sky in the constellation Leo. Anyone with a backyard telescope is encouraged to watch this easy-to-observe event. (Advice: Start watching at least 30 minutes ahead of time.)
Realtime Space Weather Photo Gallery
Realtime Aurora Photo Gallery
Every night, a network of NASA all-sky cameras scans the skies above the United States for meteoritic fireballs. Automated software maintained by NASA's Meteoroid Environment Office calculates their orbits, velocity, penetration depth in Earth's atmosphere and many other characteristics. Daily results are presented here on Spaceweather.com.
On Jan. 18, 2015, the network reported 17 fireballs.
(16 sporadics, 1 alpha Hydrid)
In this diagram of the inner solar system, all of the fireball orbits intersect at a single point--Earth. The orbits are color-coded by velocity, from slow (red) to fast (blue). [Larger image] [movies]
Potentially Hazardous Asteroids (PHAs
) are space rocks larger than approximately 100m that can come closer to Earth than 0.05 AU. None of the known PHAs is on a collision course with our planet, although astronomers are finding new ones
all the time.
On January 18, 2015 there were potentially hazardous asteroids. Notes: LD means "Lunar Distance." 1 LD = 384,401 km, the distance between Earth and the Moon. 1 LD also equals 0.00256 AU. MAG is the visual magnitude of the asteroid on the date of closest approach.
| ||The official U.S. government space weather bureau |
| ||The first place to look for information about sundogs, pillars, rainbows and related phenomena. |
| ||Researchers call it a "Hubble for the sun." SDO is the most advanced solar observatory ever. |
| ||3D views of the sun from NASA's Solar and Terrestrial Relations Observatory |
| ||Realtime and archival images of the Sun from SOHO. |
| ||from the NOAA Space Environment Center |
| ||the underlying science of space weather |